Many devices are known for effecting a reduction in the size of a particulate in a particulate-containing substance. A listing of such prior art devices is set forth in the "Description of the Prior Art" appearing in U.S. Pat. No. 4,244,531. As the prior art will reveal, various structures have been employed over the years to effect an agitation of the comminuting media to effect the desired result. Each of these various structures provides varying degrees of shear forces and impact forces for effecting the desired reduction in size of the particulate.
It is frequently desirable to cause particle size reduction of a solid contained in a liquid. Liquids are frequently wanted and desirable in the total product system. For example, liquids tend to replace undesirable gases held by the particle. Further, more uniform particle size distribution is obtainable with liquid additions and a desired reaction or bond may even be created. However, in continuous type mills, that is, mills wherein a product is continually introduced into the comminuting vessel at one end and the comminuted mixture is removed at the opposite end, a strong desire has existed for many years in providing apparatus which would quickly process the product flowing therethrough so as to increase the productivity of the mill. However, the length of time that the product remains in the mill is directly related to the particle size of the particulate desired in the output mixture. Further, considerable energy is consumed during the period of time that the mill is in operation. Thus, the cost of energy per unit of product can be greatly diminished if the amount of product being processed through the mill can be substantially increased. A need has also existed for many years for a continuous type mill wherein a particulate-containing product which is to be processed is introduced at one end and the processed mixture removed at the other end, to have a minimum of seals for preventing leakage of comminuting media as well as product to be processed from the vessel. It is highly desirable to provide a mill having only one seal while permitting product to be processed to be introduced at one end of the vessel and effectively removed at the opposite end, thereby causing the product to flow continuously through the agitated comminuting media.
Accordingly, it is an object of this invention to provide a mill for continuously processing product or batch processing product wherein the comminuting media is sufficiently agitated and with a minimum of friction occurring between the moving parts to achieve the desired amount of comminution of a particulate-containing product.
It is a further object of this invention to provide a continuous type mill, namely, a mill wherein product is introduced at one end of the vessel and the comminuted mixture removed at the opposite end, wherein the comminuting media is sufficiently agitated and with a minimum of friction occurring between the moving parts to achieve the desired amount of comminution of a particulate-containing product.
It is a further object of the invention to provide a mill, as aforesaid, wherein the speed of rotation of the vessel and related shaft and blade members is selected based on the size of the media, the density of the media and the viscosity of the product to be processed, so that the centrifugal force generated during a rotation of the vessel and related shaft and blade members will cause the media to generate a force equal to many times the weight of the media and to further provide an interruption of the movement of the comminuting media to effect a deceleration of the comminuting media only to have it reaccelerated again to generate the desired comminuting action in the media.
It is a further object of this invention to provide a mill, as aforesaid, wherein only one rotary or shaft seal structure is provided for preventing comminuting media and product from leaking out of the vessel.
It is a further object of this invention to provide a mill, as aforesaid, wherein an increase in the output of the comminuted mixture is effected thereby reducing the energy consumed in comminuting the product per unit of product produced.
It is a further object of this invention to provide a mill, as aforesaid, which is durably constructed and which will provide a generally maintenance-free operating characteristic.